Preheat your oven to 375°F (190°C).
Boil jumbo pasta shells in salted water until al dente. Drain and set aside.
In a skillet, melt butter and sauté garlic until fragrant. Add cooked chicken, Italian seasoning, salt, and pepper. Cool slightly.
In a mixing bowl, combine ricotta, mozzarella, Parmesan, and the seasoned chicken mixture. Stir well to create the filling.
In a saucepan, melt butter for the Alfredo sauce. Add garlic and cook until fragrant. Stir in cream, nutmeg, salt, and pepper. Simmer for 5 minutes. Add Parmesan and stir until melted.
Spread 1 cup of Alfredo sauce on the bottom of a baking dish.
Fill each cooked pasta shell with the chicken mixture and place them in the dish. Pour remaining Alfredo sauce over the shells.
Sprinkle mozzarella cheese on top and bake for 25 minutes, or until bubbly and golden.
Garnish with parsley and serve warm.
